The use of fiber optic technology in the communications industry continues to increase. As is known in the art, fiber optic communications provide numerous advantages such as increased bandwidth, less noise, lower signal-to-noise ratio requirements, and lower error rates. In addition, the use of fiber optic cable relative to metallic conductors permits a much larger traffic of communication to occupy the same space previously required by metallic conductors.
As known in the art, communication of signals through an optic fiber is accomplished by placing communications circuitry at the tips of both ends of the optic fiber. FIG. 1a illustrates a perspective view of certain components of such a system. Specifically, FIG. 1a illustrates a carrier 10 which is commonly disposed within a fiber optics package (shown in FIG. 1b). As known in the art, carrier 10 supports various components including a thermistor 12 and a back-wave detector 14. Carrier 10 further supports a U-shaped subcarrier 16. A submount 18 is disposed on top of subcarrier 16 and supports a laser 20.
Carrier 10 further includes an integral extension 21 which supports an adjustment post 22. A small mass of solder (not shown) supports a fiber retaining slab 24 on top of adjustment post 22. Slab 24 includes a longitudinal groove 26 on the order of 0.01 inches in width. An optic fiber 28 extends from a sleeve 30 and is retained within groove 26. The tip 32 of fiber 28 extends inwardly beyond the edge of slab 24 and immediately proximate laser 20. Thus, laser 20 can communicate signals to and from fiber 28 by either sensing signals or transmitting signals to tip 32 of the fiber.
FIG. 1b illustrates a perspective and cutaway view of carrier 10 when disposed within a prior art fiber optics package 34. Package 34 is typically a parallelepiped in shape having a length on the order of 1.0 inch and a width and height on the order of 0.75 inches. Package 34 is carefully constructed to hermetically house various components, including carrier 10. A ferrule 36 permits access through a hole or "pass through" in one side of package 34. Sleeve 30 passes through ferrule 36, thereby permitting optic fiber 28 to extend into the interior of package 34. Typically, solder 38 or an alternative sealant is used at the interface between sleeve 30 and ferrule 36 so that contaminants may not pass via this interface into the interior of package 34. A thermal electric cooler 39 supports carrier 10 and its associated componentry. In addition, package 34 houses an integrated circuit 40 which connects in various manners to the componentry of carrier 10, and also to a series of package pins 42. A pair of power conductors 43a are connected to respective power pins 43b. Thus, signal interaction to the communications circuitry and power supply to thermal electric cooler 39 may be accomplished external from package 34 by accessing pins 42 and 43b.
In the prior art embodiment of FIGS. 1a-b, optic fiber 28 is commonly affixed within retaining slab 24 by use of solder (for a metalized fiber) or epoxies (typically, for a non-metalized fiber). Specifically, either of these materials are used to form deposits 44 and 46 along slab 24 to retain fiber 28 along groove 26. While performing their respective retention function, each of these materials provides various drawbacks and potential problems in connection with the overall system. For example, as is known in the art, solder tends to move or creep over time due to stress. As another example, solder creates a known ratcheting effect due to fluctuations in temperature. Thus, both the solder used as deposits 44 and 46 as well as the solder between post 22 and slab 24 may tend to change position over the life-span of the system. Such a change correspondingly moves the otherwise fixed position of tip 32 of optic fiber 28. As is known in the art, tolerances for movement of tip 32 are typically only on the order of 0.1 to 1.5 microns. Naturally, therefore, excessive movement of tip 32 is unacceptable and may reduce or eliminate the ability of the system to communicate along optic fiber 28. Conductive epoxy and like materials also suffer due to their corrosive and/or contaminating effects. In addition, quite often these materials produce gaseous byproducts which may interfere with the sensitive operation of laser 20. Thus, these materials also present a risk to the long term reliability of the system of FIGS. 1a-1b.
It is therefore an object of the present invention to provide a method and apparatus for precisely affixing an optic fiber tip in position with respect to a fiber communications circuit.
It is a further object of the present invention to provide such a method and apparatus for reducing the possibility of subsequent movement of an optic fiber tip with respect to its associated communications circuit.
It is a further object of the present invention to provide such a method and apparatus for reducing the amount of contaminants implemented when affixing the tip of an optic fiber proximate its associated communications circuit.
It is a further object of the present invention to provide such a method and apparatus for providing improved axial and radial adjustment of the tip of an optic fiber with respect to its associated communications circuit.
Still other objects and advantages of the present invention will become apparent to those of ordinary skill in the art having reference to the following specification together with its drawings.